Effects of LBP on murine N9 microglial cell N9 cells were treated with different medicines. The iNOS level was shown as relative number to that of the vehicle group, and the Arg1 level and iNOS/Arg1 ratio were normalized to that of IL-4 group. Vehicle treated N9 cells displayed mild iNOS and little Arg1. LPS + IFNγ and IL-4 induced markedly enhanced M1 and obvious M2, respectively. LBP alone and allied with IL-4 led to increased iNOS and suppressed Arg1 expression, compared to vehicle and IL-4, respectively. *p < 0.05, **p < 0.01, compared to the corresponding controls treated with same medicine short of LBP.